热液条件下CO2和H2反应合成丁烷和戊烷

热液条件下CO2和H2通过费托合成反应产生烷烃从热力学上来说是可行的,但是,前人的实验研究表明,如果没有合适的催化剂,该反应难以进行,并且烷烃产物的种类依赖于催化剂的种类和性质.在镍铁矿的催化作用下,热液中的CO2和H2能够反应形成CH4,在铬铁矿催化作用下反应能够产生CH4、C2H6和C3Ha.热液条件下,CO2和H2能否反应形成碳数大于3的烷烃,还需要进一步的催化实验加以查证.本研究在300℃、30 MPa条件下进行实验,以Fe、CoCl2和13C标识的NaH13CO3在NaCl溶液中反应.13C同位素示踪结果表明,实验反应过程中CO2和H2反应形成了丁烷和戊烷.     

碳酸盐倒退溶解模式的化学热力学基础——与H_2S有关的溶解介质及其与CO_2的对比

以化学热力学中的吉布斯自由能增量为基础,计算了与H2S(g)/ H2S(aq) /HS-/ H+/S2-系统有关反应在不同温度下的平衡常数,同时根据方解石和白云石在酸性条件下的溶解过程,获得了这两种碳酸盐矿物溶解过程中地层中流体pH值与PCO2、地层压力和埋藏深度的关系。在此基础上,对比了从地表到深埋藏的温度和压力条件下,与CO2和H2S有关的酸性介质对流体\[H+\]贡献的差异性,以及对于碳酸盐溶解作用的差异性。计算结果表明:1）无论以CO2还是以H2S作为溶解介质,温度增加和（或）PCO2增加,都会造成方解石和白云石溶解所需要的\[H+\]增加,在深埋藏相对高温和高压条件下,高PCO2条件会使得碳酸盐矿物的溶解更加困难,如果\[H+\]受到缓冲,CO2的增加不仅不能造成碳酸盐矿物的溶解,反而会造成碳酸盐矿物的沉淀;2）无论在何种酸性介质中,碳酸盐矿物的倒退溶解模式在化学上都是成立的,低温的成岩环境,深部地层中高温流体的向上运移、构造抬升所造成的温度降低（-ΔT）都会提高H2S和（或）CO2流体（也包括其它酸性介质）对碳酸盐矿物溶解能力;3）在地表和近地表条件下（几百米深度范围内）,在同时存在CO2和H2S的环境中,CO2对应酸的电离提供的\[H+\]略多于H2S对应酸的电离,与CO2有关的酸性流体对碳酸盐矿物溶解相对重要,而在深埋藏条件下、尤其是深度大于4 000 m的深埋藏地层中,H2S对应酸的电离提供的\[H+\]显著大于CO2,其对碳酸盐矿物的溶解更为重要,在存在硫酸盐还原作用的深埋藏地层中,碳酸盐的深部溶解作用会更为发育,这可能是川东北地区深埋藏条件下次生孔隙发育的重要原因之一。     

四川盆地东北部三叠系飞仙关组硫酸盐还原作用对碳酸盐成岩作用的影响

四川盆地东北部三叠系飞仙关组存在广泛的硫酸盐还原作用,同时地层中也存在锶含量异常高的成岩流体。研究表明:热化学硫酸盐还原作用（TSR）和（或）细菌硫酸盐还原作用（BSR）造成的SO42-离子的消耗对成岩孔隙流体中SrSO4溶解度的改变是三叠系中高Sr成岩流体的形成机制之一,该机制使得孔隙流体从白云石化作用和碳酸盐矿物的新生变形作用中获得的Sr在流体中以高浓度的Sr2+形式存在,并使之在流体中极度富集,这也是四川盆地东北部三叠系中大型和超大型天青石矿床的形成机制之一。H2S和CO2是硫酸盐还原作用的重要产物,不同温度条件下溶于水中的H2S和CO2,与不溶于水的气体分子之间的平衡反应H2S（aq）H2S(g)和CO2(aq)CO2(g)的平衡常数和吉布斯自由能增量计算表明,当温度从25℃升高至220℃时,两个反应的平衡常数分别大致从10增至240和从20增至500,两个反应的平衡常数都始终大于1,说明H2S和CO2更趋向于以气体形式存在,同时温度越高,系统中以气体形式存在的H2S和CO2会越多,溶解于水中的H2S和CO2会越少,因而在深埋藏的高温条件下,H2S和CO2对碳酸盐矿物的溶解能力可能相对很小。相对低温的成岩环境、高温流体的向上和侧向运移、构造抬升、富氧流体与含有H2S流体的混合以及金属硫化物的沉淀是提高含H2S和（或）CO2流体对碳酸盐矿物溶解能力的五个途径。因此,与较早成岩阶段相对浅埋藏环境的碳酸盐溶解作用有关的H2S和CO2流体可能与细菌硫酸盐还原作用（BSR）关系更为密切;断层或其它流体运移通道是高温含有H2S和CO2流体向上运移的基础条件,具有原生孔隙度和渗透率的礁、滩相高能沉积物也是流体发生侧向运移的先决条件;大幅度的构造抬升造成的地层温度降低是提高含H2S和（或）CO2地层流体对碳酸盐矿物溶解能力的重要因素,地壳抬升至近地表造成的古喀斯特作用也可以为H2S的氧化提供良好的地质环境。在有关的勘探中应注意:在断层等流体运移通道造成高温含H2S和CO2流体向上运移的条件下,与之有关的构造低点应该是主要的勘探目标;在燕山运动导致的地层抬升并导致深部热流体降温的条件下,与之有关的构造高点应该是主要的勘探目标,应分别对待。     

吸附势理论在煤层气吸附/解吸中的应用

煤层气的吸附/解吸将导致煤层甲烷碳同位素以及煤层气多组分分馏,使得煤层气富集区预测成为可能;并为揭示注入CO2增强CH4产出提供依据。本文根据Polanyi吸附势理论和实测及收集的等温吸附试验数据,探讨煤层甲烷碳同位素和多组分气体的分馏。通过研究,得到如下两个结论：①13CH4在煤表面的吸附势普遍高于12CH4,也就是说13CH4与12CH4相比具有优先吸附、滞后解吸的特点。这种差异具有随压力增加而增加的特点。②煤层气吸附/解吸过程中CH4和CO2的分馏可归纳为以下3种情形： a. CO2和CH4的吸附/解吸等温线不相交,CO2的吸附势大于等于CH4,在CO2和CH4吸附势接近的中压阶段(1~2.5 MPa)不利于注CO2驱CH4,高压、低压阶段均有利; b. 因CH4的吸附/解吸等温线相交造成CH4和CO2的吸附特性曲线相交,在高压条件(>2.5 MPa)下利于注CO2驱CH4; c. 因CO2的吸附/解吸等温线相交造成CH4和CO2的吸附特性曲线相交,在高压条件(>2.5 MPa)下利于注CO2驱CH4。吸附势理论的引入为定量评价注入二氧化碳驱甲烷工艺参数和有利储层的选择提供了方法,并揭示了在高压条件(>2.5 MPa)下总是有利于向煤层注入CO2强化CH4产出。     

柴达木西部钻孔盐类矿物及环境意义初步研究

柴达木盆地位于青藏高原北部,沉积和储存了巨量的蒸发岩。其独特的地理位置、构造特征、盐类沉积和其它资源优势,成为地学领域各方向学者关注的焦点。2008年,中德合作在盆地西部取得千米深的钻孔,上部400 m表现为碳酸盐粘土层与盐层的交替,盐层的矿物种类是石盐（NaCl）,石膏（CaSO4·2H2O）,芒硝（Na2SO4·10H2O）,无水芒硝（Na2SO4）,钙芒硝（Na2Ca(SO4)2）,杂卤石（K2MgCa2(SO4)4·2H2O）,尤钠钙矾（Na4Ca(SO4)3·2H2O）和白钠镁矾（Na2Mg(SO4)2·4H2O）,以石盐和石膏为主。碳酸盐粘土层中还出现了少量重晶石（BaSO4）、碳酸钠钙石（Ca2Na2(CO3)3）、钠钙矾（Ca2Na3(SO4)3(OH)）、苏打石（NaHCO3）、斜碳钠钙石（Na2Ca(CO3)2·5H2O）、一水碳酸钠（Na2CO3·H2O）和水硼镁石（CaMg(B3O3(OH)5)2·6H2O）。碳酸盐粘土层中不同形态的石膏单晶、双晶和集合体,形成于次生浓卤水溶液,晶体形状与生长速度、溶液性质和环境条件有关。单盐矿物石盐、石膏和无水芒硝从卤水中直接结晶,复盐钙芒硝、白钠镁矾和尤钠钙矾则由单盐反应形成。尤钠钙矾为罕见的亚稳定矿物,柴达木盆地和青藏高原其它地区的研究中尚未见报道,该矿物形成温度远高于室温,可能是由石膏或无水芒硝在富Na SO4卤水溶液中反应形成。根据矿物种类、组合和阳离子含量推断,古卤水类型主要为Na Cl型,其次为Na Ca SO4、Na SO4、Na SO4 Cl、Na Ca SO4 Cl,少数层位为Ca SO4和Na Mg SO4型卤水。盐层和碳酸盐粘土层的交替说明,1 Ma以来钻孔所在区域为干湿交替气候,18个成盐阶段或气候干旱阶段出现在0.97~0.03 Ma,最早的两个蒸发阶段为0.96~0.97 Ma和0.87 Ma,其它蒸发阶段出现在0.78~0.03 Ma,厚盐层集中出现在0.5~0.03 Ma。     

有机质碳同位素热力学分馏与天然气碳同位素组成

干酪根中不同结构和官能团具有不同的碳同位素组成,这种差异可以用有机质碳同位素热力学同位素因子（β因子）进行预测。煤岩模拟实验产物中,δ13CCO2相对烃类气体而言明显偏重,这与干酪根中羧基的β13C较大有关。含水实验产物的δ13CCO2轻于无水实验产物的δ13CCO2是由于含水实验中所增加CO2的碳同位素组成相对较轻造成的,含水实验增加的CO2产率是由β13C相对较小的部分亚甲基碳通过断裂、氢转移、以及与水反应转变而来。模拟实验低温阶段（≤300℃）,甲氧基中的甲基断裂可能的甲烷形成的主要方式。而甲氧基的β13C大于甲基,所以低温阶段出现了甲烷碳同位素组成先较重后变轻的现象。     

超临界萃取技术在泥炭纤维素提纯中的应用与萃取组分特征

将超临界CO2萃取技术应用于泥炭纤维素中有机脂类物质的提纯工作,并对萃取物进行色—质联用分析。结果表明,在萃取物中检出了一系列甲酯类、乙酯类、少量有机酸及正构烷烃组分。首次检出的脂肪酸乙酯系列化合物多数呈高碳数分布,具偶碳优势。长链正构烷烃主峰碳为nC33或nC31,具有明显的奇碳优势,这在一定程度上反映了泥炭生成过程的气候条件,记录了气候变化的信息。同时也显示出超临界CO2萃取技术能够很好地完成除去纤维素中有机脂类这一重要环节,有利于提高泥炭纤维素δ13C值检测的准确度,为超临界流体萃取技术在地学中的应用开辟了一个新途径。     

交互四元体系Li+, Mg2+//SO2-4, B4O2-7H2O 288 K

采用等温溶解平衡法研究了288K时Li+, Mg2+//SO2-4, B4O2-7- H2O四元体系的固液相平衡关系,测定了该四元体系在288K时平衡液相的溶解度和密度。依据实验测定的平衡溶解度数据及对应的平衡固相,绘制了该四元体系的平衡相图及密度组成图。研究结果表明：交互四元体系Li+, Mg2+//SO2-4, B4O2-7- H2O 288K时平衡相图中有2个共饱点,5条单变量曲线,4个结晶区对应的平衡固相分别为Li2B4O7·3H2O,Li2SO4·H2O,MgB4O7·9H2O和MgSO4·7H2O。     

江苏金湖凹陷古近系奇碳优势和偶碳优势共存的正构烷烃

苏北盆地金湖凹陷古近纪阜宁组二段暗色泥岩及其生成的原油中,正构烷烃系列存在着偶碳优势、奇碳优势以及二者共存的3种分布型式。本文重点探讨正构烷烃奇碳优势和偶碳优势共存的形成原因。在这类暗色泥岩与原油中,正构烷烃通常低碳数部分呈nC15、nC17优势,中碳数具有nC20、nC22优势,高碳数为nC25、nC27、nC29、nC31优势;并且具有强烈的植烷优势、较高的伽玛蜡烷指数、含有一定量β胡萝卜烷和C24四环萜烷。分析认为沉积水体环境和有机质来源的变化决定了正构烷烃的分布形式,该类正构烷烃形成于湖盆水体盐度分层的沉积环境,主要来源于湖盆内藻类和湖盆外高等植物蜡。      

海洋N2O的研究进展

N2O在大气中的浓度仅为CO2的浓度的千分之一左右,但在同等浓度的情况下温室效应却是CO2的200~300倍;它在大气层中的光化学产物会与臭氧反应,从而损耗平流层的臭氧。N2O的环境效应引起人们的关注,许多国际气候变化研究项目都把其列入重要研究内容。通过对过去40年的相关研究工作进行综合分析,阐述N2O在海洋中的分布规律和其影响因素、产生的机制、它的海气通量及其影响因素,从而揭示N2O的海洋生物地球化学循环过程以及这一过程对全球氮循环的贡献。     

Pyrite-hydrocarbon Interaction under Hydrothermal Conditions: an Alternative Origin of H2S and Organic Sulfur Compounds in Sedimentary Environments

Sulfate rocks and organic sulfur from sedimentary organic matter are conventionally assumed as the original sulfur sources for hydrogen sulfide(H_2S) in oil and gas reservoirs. However,a few recent experiments preliminarily indicate that the association of pyrite and hydrocarbons may also have implications for H_2S generation,in which water effects and natural controls on the evolution of pyrite sulfur into OSCs and H_2S have not been evaluated. In this study,laboratory experiments were conducted from 200 to 450° C to investigate chemical interactions between pyrite and hydrocarbons under hydrothermal conditions. Based on the experimental results,preliminary mechanism and geochemical implications were tentatively discussed. Results of the experiments showed that decomposition of pyrite produced H_2S and thiophenes at as low as 330°C in the presence of water and n-pentane. High concentrations of H_2S were generated above 450°C under closed pyrolysis conditions no matter whether there is water in the designed experiments. However,much more organic sulfur compounds(OSCs) were formed in the hydrous pyrolysis than in anhydrous pyrolysis. Generally,most of sulfur liberated from pyrite at elevated temperatures was converted to H_2S. Water was beneficial to breakdown of pyrite and to decomposition of alkanes into olefins but not essential to formation of large amounts of H_2S,given the main hydrogen source derived from hydrocarbons. In addition,cracking of pyrite in the presence of 1-octene under hydrous conditions was found to proceed at 200°C,producing thiols and alkyl sulfides. Unsaturated hydrocarbons would be more reactive intermediates involved in the breakdown of pyrite than alkanes. The geochemistry of OSCs is actually controlled by various geochemical factors such as thermal maturity and the carbon chain length of the alkanes. This study indicates that the scale of H_2S gas generated in deep buried carbonate reservoirs via interactions between pyrite and natural gas should be much smaller than that of thermochemical sulfate reduction(TSR) due to the scarcity of pyrite in carbonate reservoirs and the limited amount of long-chained hydrocarbons in natural gas. Nevertheless,in some cases,OSCs and/or low contents of H_2S found in deep buried reservoirs may be associated with the deposited pyrite-bearing rock and organic matters(hydrocarbons),which still needs further investigation.     

Abiotic formation of hydrocarbons under hydrothermal conditions: Constraints from chemical and isotope data

To understand reaction pathways and isotope systematics during mineral-catalyzed abiotic synthesis of hydrocarbons under hydrothermal conditions, experiments involving magnetite and CO₂ and H₂-bearing aqueous fluids were conducted at 400 °C and 500 bars. A robust technique for sample storage and transfer from experimental apparatus to stable isotope mass spectrometer provides a methodology for integration of both carbon and hydrogen isotope characterization of reactants and products generated during abiogenic synthesis experiments. Experiments were performed with and without pretreatment of magnetite to remove background carbon associated with the mineral catalyst. Prior to experiments, the abundance and carbon isotope composition of all carbon-bearing components were determined. Time-series samples of the fluid from all experiments indicated significant concentrations of dissolved CO and C₁-C₃ hydrocarbons and relatively large changes in dissolved CO₂ and H₂ concentrations, consistent with formation of additional hydrocarbon components beyond C₃. The existence of relatively high dissolved alkanes in the experiment involving non-pretreated magnetite in particular, suggests a complex catalytic process, likely involving reinforcing effects of mineral-derived carbon with newly synthesized hydrocarbons at the magnetite surface. Similar reactions may be important mechanisms for carbon reduction in chemically complex natural hydrothermal systems. In spite of evidence supporting abiotic hydrocarbon formation in all experiments, an “isotopic reversal” trend was not observed for ¹³C values of dissolved alkanes with increasing carbon number. This may relate to the specific mechanism of carbon reduction and hydrocarbon chain growth under hydrothermal conditions at elevated temperatures and pressures. Over time, significant ¹³C depletion in CH₄ suggests either depolymerization reactions occurring in addition to synthesis, or reactions between the C₁-C₃ hydrocarbons and carbon species absorbed on mineral surfaces and in solution.     

The influence of carbon source on abiotic organic synthesis and carbon isotope fractionation under hydrothermal conditions

A series of laboratory experiments were performed to investigate the relative contributions of CO and other single-carbon compounds to abiotic synthesis of organic compounds in hydrothermal environments. Experiments were conducted by heating aqueous solutions of CO, CO₂, HCOOH, or CH₄ at 250 °C under reducing conditions, and observing production of CH₄ and other hydrocarbons. Native Fe was included in the experiments as a source of H₂ through reaction with water and as a potential catalyst. Experiments with CO or HCOOH as the carbon source resulted in rapid generation of CH₄ and other hydrocarbons that closely resembled typical products of Fischer-Tropsch organic synthesis. In contrast, experiments using CO₂ or CH₄ as the carbon source yielded no detectable hydrocarbon products. Carbon isotope measurements of reaction products from the CO experiments indicate that the CH₄ and other hydrocarbons were substantially depleted in ¹³C, with CH₄ δ¹³C values 30 to 34‰ lighter than the initial CO. Most of the fractionation apparently occurs during attachment of CO to the catalyst surface and subsequent reduction to surface-bound methylene. The initial step in polymerization of these methylene units to form hydrocarbons involves a small, positive fractionation, so that ethane and ethene are slightly enriched in ¹³C relative to CH₄. However, subsequent addition of carbon molecules to the growing hydrocarbon chain proceeds with no net observable fractionation, so that the isotopic compositions of the C₃₊ light hydrocarbons are controlled by isotopic mass balance. This result is consistent with a previously proposed model for carbon isotopic patterns of light hydrocarbons in natural samples. The abundance and isotopic composition of light hydrocarbons produced with HCOOH as the carbon source were similar to those generated with CO, but the isotopic compositions of non-volatile hydrocarbons diverged, suggesting that the higher hydrocarbons were formed by different mechanisms in the CO and HCOOH experiments. The experiments indicate that CO, and possibly HCOOH, may be critical intermediates in the abiotic formation of organic compounds in geologic environments, and suggest that the low levels of these compounds present in most hydrothermal systems could represent a bottleneck restricting the extent of abiotic organic synthesis in some circumstances.     

Elevated concentrations of formate, acetate and dissolved organic carbon found at the Lost City hydrothermal field

Fluids from the ultramafic-hosted Lost City hydrothermal field were analyzed for total dissolved organic carbon and dissolved organic acids. Formate (36-158 μmol/kg) and acetate (1-35 μmol/kg) concentrations are higher than in other fluids from unsedimented hydrothermal vents, and are a higher ratio of the total dissolved organic carbon than has been found in most marine geothermal systems. Isotopic evidence is consistent with an abiotic formation mechanism for formate, perhaps during serpentinization processes in the sub-surface. Further support comes from previous studies where the abiological formation of low molecular weight organic acids has been shown to be thermodynamically favorable during hydrothermal alteration of olivine, and laboratory studies in which the reduction of carbon dioxide to formate has been confirmed. As the second most prevalent carbon species after methane, formate may be an important substrate to microbial communities in an environment where dissolved inorganic carbon is limited. Acetate is found in locations where sulfate reduction is believed to be important and is likely to be a microbial by-product, formed either directly by autotrophic metabolic activity or indirectly during the fermentative degradation of larger organic molecules. Given the common occurrence of exposed ultramafic rocks and active serpentinization within the worlds ocean basins, the abiotic formation of formate may be an important process supporting life in these high pH environments and may have critical implications to understanding the organic precursors from which life evolved.     

SOVESTKAYA GEOLOGIYA (SOVIET GEOLOGY) IN COVER-TO-COVER TRANSLATION, 1961 NO. 1

Parts of certain alkalic intrusive massifs contain up to 63 cc methane per kilogram of rock, with smaller amounts of heavier hydrocarbon gases, bitumen, hydrogen, carbon monoxide and carbon dioxide. The authors argue that the hydrocarbons cannot have come from assimilated limestone, because the igneous rocks contain much more of these gases than do the enclosing limestones. Likewise, the hydrocarbons cannot have been introduced by late solutions because they are much lower in hydrothermal and metasomatic fades than in primary minerals of the high temperature intrusive facies. Hydrocarbons are not stable at magmatic temperatures; the authors conclude that these must have formed in the presence of natural catalysts during slow cooling below 500°C, in accordance with industrial synthesis of hydrocarbons. The C¹²/C¹³ ratio of the bitumens is in the range for ordinary petroleum, suggesting that they formed at relatively low temperature, but the carbon of the gaseous hydrocarbons is lighter, which may indicate that they formed at somewhat higher temperatures. -- E. Ingerson.     

利用多年冻土区湖相沉积物中埋藏植物稳定碳同位素组成重建大气CO2浓度

沉水植物碳同位素分馏同水中溶解无机碳浓度有一定的关系，因而可以通过青藏高原多年冻土区的湖相沉积物中埋藏沉水植物－－龙须眼子菜（Potamogeton pectinatus)植物屑的碳同位素组成重建该地大气CO2浓度的变化情形，研究结果表明，该地在9．17－6．77ka BP间，大气CO2浓度是整个研究时间段中最低的，其后在6．77－4．56ka BP时期大气CO2浓度增加，在4．56－2．17ka BP之间，大气CO2浓度是整个研究时间内CO2浓度最高的阶段，植物屑的碳同位素组成反映了溶解无机碳浓度的变化，从而可用以重建大气CO2浓度的变化情况。     

Carbon dioxide stripping from anaerobic digestate of food waste using two types of aerators

Anaerobic digestate of organic wastes often contains high concentrations of ammonia and carbon dioxide. Ammonia can be removed from digestate by air stripping at elevated pH. However, it is difficult to increase pH of the digestate because dissolved carbon dioxide transforms into bicarbonate and carbonate ions. Thus, carbon dioxide in digestate needs to be removed to reduce alkali consumption in ammonia stripping process. This study aimed to optimize and compare the performances of diffused and packed tower aerators for anaerobic digestate of food waste. The diffused aerator removed 82.1% of dissolved carbon dioxide and 13.7% of total inorganic carbon, and increased pH of digestate from pH 7.87 to pH 8.53, under the following optimized conditions; digestate temperature of 45 °C, air flow rate of three volumes of air added to a unit volume of liquid per minute, aspect ratio of 2, agitation speed of 500 rpm with a turbine impeller, and retention time of 10 min. Operating conditions of the packed tower aerator were also optimized, and it was found that the packed tower aerator removed 15% and 44% less dissolved carbon dioxide and total inorganic carbon, respectively, than the diffused aerator. It was also found that overall coefficients of carbon dioxide mass transfer from liquid to gas phase determined the final pH of digestate and removal efficiencies of carbon species.     

Predictive isotopic biogeochemistry: hydrocarbons from anoxic marine basins

Carbon isotopic compositions were determined for individual hydrocarbons in water column and sediment samples from the Cariaco Trench and Black Sea. In order to identify hydrocarbons derived from phytoplankton, the isotopic compositions expected for biomass of autotrophic organisms living in surface waters of both localities were calculated based on the concentrations of CO2(aq) and the isotopic compositions of dissolved inorganic carbon. These calculated values are compared to measured delta values for particulate organic carbon and for individual hydrocarbon compounds. Specifically, we find that lycopane is probably derived from phytoplankton and that diploptene is derived from the lipids of chemoautotrophs living above the oxic/anoxic boundary. Three acyclic isoprenoids that have been considered markers for methanogens, pentamethyleicosane and two hydrogenated squalenes, have different delta values and apparently do not derive from a common source. Based on the concentration profiles and isotopic compositions, the C31 and C33 n-alkanes and n-alkenes have a similar source, and both may have a planktonic origin. If so, previously assigned terrestrial origins of organic matter in some Black Sea sediments may be erroneous.     

祁连山冻土区天然气水合物分解气碳氢同位素组成特征

开展祁连山冻土区天然气水合物气体同位素研究,是解决其气体成因、来源等科学问题的一个重要手段。本研究采集祁连山南麓多年冻土区水合物科学钻探DK2和DK3孔共8个含水合物的岩芯样品,采用真空顶空法收集样品中水合物的分解气,分别用气相色谱(GC)、气相色谱同位素比值质谱(GC-IRMS)测定其气体成分和同位素组成,测试结果表明:祁连山冻土区天然气水合物样品的气体碳氢同位素变化较大,甲烷、乙烷和丙烷的碳同位素(δ13C)变化范围分别为-52.6‰～-48.1‰、-38.6‰～-30.7‰和-34.7‰～-21.2‰,而二氧化碳的碳同位素(δ13C)最低为-27.9‰,最高为16.7‰;甲烷、乙烷和丙烷的氢同位素(δD)变化范围分别为-285‰～-227‰、-276‰～-236‰和-247‰～-198‰。通过对这些碳氢同位素进行综合研究,包括气体分子组成与同位素的关系分析、甲烷的碳氢同位素之间的关系判断等,结果表明研究区天然气水合物的气体主要来源于热解气,而且是在淡水环境中形成的有机成因气。     

金刚石伴生矿物中的烃类包裹体问题(英文)

首次在Mir金伯利岩筒中的锆石中发现了烃类包裹体。利用低温荧光光谱仪测定出烃类包裹体的成分为萘和菲的同系物 ,芘 ,1,12苯并芘等 ;其成分与Udachnaya岩筒中的橄榄石内的烃类和Mir岩筒中的石榴石中的烃类的成分相近。测定出锆石的δ13C值为 - 2 1 83‰～ - 3 3 5 4‰ ,与用榴辉岩共生组合中最轻的金刚石测出的同位素δ13C值范围相符。文中引述了有关有机物来源的讨论及多环芳烃 (PAH)由缩聚作用形成的论述。伴生矿物中相当数量的PAH的存在证明在形成金刚石及其伴生矿物的情况下 ,若有相当浓度的自由氢存在则可能发生缩聚作用。这些缩聚作用中碳的来源显然与形成金刚石时碳的来源是相同的 (即液态的CH4,CO及CO2 )。